// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for Linear Technology LTC2945 I2C Power Monitor
 *
 * Copyright (c) 2014 Guenter Roeck
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/regmap.h>

/* chip registers */
#define LTC2945_CONTROL                 0x00
#define LTC2945_ALERT                   0x01
#define LTC2945_STATUS                  0x02
#define LTC2945_FAULT                   0x03
#define LTC2945_POWER_H                 0x05
#define LTC2945_MAX_POWER_H             0x08
#define LTC2945_MIN_POWER_H             0x0b
#define LTC2945_MAX_POWER_THRES_H       0x0e
#define LTC2945_MIN_POWER_THRES_H       0x11
#define LTC2945_SENSE_H                 0x14
#define LTC2945_MAX_SENSE_H             0x16
#define LTC2945_MIN_SENSE_H             0x18
#define LTC2945_MAX_SENSE_THRES_H       0x1a
#define LTC2945_MIN_SENSE_THRES_H       0x1c
#define LTC2945_VIN_H                   0x1e
#define LTC2945_MAX_VIN_H               0x20
#define LTC2945_MIN_VIN_H               0x22
#define LTC2945_MAX_VIN_THRES_H         0x24
#define LTC2945_MIN_VIN_THRES_H         0x26
#define LTC2945_ADIN_H                  0x28
#define LTC2945_MAX_ADIN_H              0x2a
#define LTC2945_MIN_ADIN_H              0x2c
#define LTC2945_MAX_ADIN_THRES_H        0x2e
#define LTC2945_MIN_ADIN_THRES_H        0x30
#define LTC2945_MIN_ADIN_THRES_L        0x31

/* Fault register bits */

#define FAULT_ADIN_UV           (1 << 0)
#define FAULT_ADIN_OV           (1 << 1)
#define FAULT_VIN_UV            (1 << 2)
#define FAULT_VIN_OV            (1 << 3)
#define FAULT_SENSE_UV          (1 << 4)
#define FAULT_SENSE_OV          (1 << 5)
#define FAULT_POWER_UV          (1 << 6)
#define FAULT_POWER_OV          (1 << 7)

/* Control register bits */

#define CONTROL_MULT_SELECT     (1 << 0)
#define CONTROL_TEST_MODE       (1 << 4)

static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
        { .compatible = "adi,ltc2945" },
        { }
};
MODULE_DEVICE_TABLE(of, ltc2945_of_match);

/**
 * struct ltc2945_data - LTC2945 device data
 * @regmap: regmap device
 * @shunt_resistor: shunt resistor value in micro ohms (1000 by default)
 */
struct ltc2945_data {
        struct regmap *regmap;
        u32 shunt_resistor;
};

static inline bool is_power_reg(u8 reg)
{
        return reg < LTC2945_SENSE_H;
}

/* Return the value from the given register in uW, mV, or mA */
static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
{
        struct ltc2945_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u32 shunt_resistor = data->shunt_resistor;
        unsigned int control;
        u8 buf[3];
        long long val;
        int ret;

        ret = regmap_bulk_read(regmap, reg, buf,
                               is_power_reg(reg) ? 3 : 2);
        if (ret < 0)
                return ret;

        if (is_power_reg(reg)) {
                /* 24-bit power */
                val = (buf[0] << 16) + (buf[1] << 8) + buf[2];
        } else {
                /* 12-bit current, voltage */
                val = (buf[0] << 4) + (buf[1] >> 4);
        }

        switch (reg) {
        case LTC2945_POWER_H:
        case LTC2945_MAX_POWER_H:
        case LTC2945_MIN_POWER_H:
        case LTC2945_MAX_POWER_THRES_H:
        case LTC2945_MIN_POWER_THRES_H:
                /*
                 * Convert to uW
                 * Control register bit 0 selects if voltage at SENSE+/VDD
                 * or voltage at ADIN is used to measure power.
                 */
                ret = regmap_read(regmap, LTC2945_CONTROL, &control);
                if (ret < 0)
                        return ret;
                if (control & CONTROL_MULT_SELECT) {
                        /* 25 mV * 25 uV = 0.625 uV resolution. */
                        val *= 625LL;
                } else {
                        /* 0.5 mV * 25 uV = 0.0125 uV resolution. */
                        val = (val * 25LL) >> 1;
                }
                val *= 1000;
                /* Overflow check: Assuming max 24-bit power, val is at most 53 bits right now. */
                val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
                /*
                 * Overflow check: After division, depending on shunt resistor,
                 * val can still be > 32 bits so returning long long makes sense
                 */

                break;
        case LTC2945_VIN_H:
        case LTC2945_MAX_VIN_H:
        case LTC2945_MIN_VIN_H:
        case LTC2945_MAX_VIN_THRES_H:
        case LTC2945_MIN_VIN_THRES_H:
                /* 25 mV resolution. Convert to mV. */
                val *= 25;
                break;
        case LTC2945_ADIN_H:
        case LTC2945_MAX_ADIN_H:
        case LTC2945_MIN_ADIN_THRES_H:
        case LTC2945_MAX_ADIN_THRES_H:
        case LTC2945_MIN_ADIN_H:
                /* 0.5mV resolution. Convert to mV. */
                val = val >> 1;
                break;
        case LTC2945_SENSE_H:
        case LTC2945_MAX_SENSE_H:
        case LTC2945_MIN_SENSE_H:
        case LTC2945_MAX_SENSE_THRES_H:
        case LTC2945_MIN_SENSE_THRES_H:
                /* 25 uV resolution. Convert to mA. */
                val *= 25 * 1000;
                /* Overflow check: Assuming max 12-bit sense, val is at most 27 bits right now */
                val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
                /* Overflow check: After division, <= 27 bits */
                break;
        default:
                return -EINVAL;
        }
        return val;
}

static long long ltc2945_val_to_reg(struct device *dev, u8 reg,
                                    unsigned long long val)
{
        struct ltc2945_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u32 shunt_resistor = data->shunt_resistor;
        unsigned int control;
        int ret;

        /* Ensure we don't overflow */
        val = clamp_val(val, 0, U32_MAX);

        switch (reg) {
        case LTC2945_POWER_H:
        case LTC2945_MAX_POWER_H:
        case LTC2945_MIN_POWER_H:
        case LTC2945_MAX_POWER_THRES_H:
        case LTC2945_MIN_POWER_THRES_H:
                /*
                 * Control register bit 0 selects if voltage at SENSE+/VDD
                 * or voltage at ADIN is used to measure power, which in turn
                 * determines register calculations.
                 */
                ret = regmap_read(regmap, LTC2945_CONTROL, &control);
                if (ret < 0)
                        return ret;
                if (control & CONTROL_MULT_SELECT) {
                        /* 25 mV * 25 uV = 0.625 uV resolution. */
                        val *= shunt_resistor;
                        /* Overflow check: Assuming 32-bit val and shunt resistor, val <= 64bits */
                        val = DIV_ROUND_CLOSEST_ULL(val, 625 * 1000);
                        /* Overflow check: val is now <= 44 bits */
                } else {
                        /* 0.5 mV * 25 uV = 0.0125 uV resolution. */
                        val *= shunt_resistor;
                        /* Overflow check: Assuming 32-bit val and shunt resistor, val <= 64bits */
                        val = DIV_ROUND_CLOSEST_ULL(val, 25 * 1000) * 2;
                        /* Overflow check: val is now <= 51 bits */
                }
                break;
        case LTC2945_VIN_H:
        case LTC2945_MAX_VIN_H:
        case LTC2945_MIN_VIN_H:
        case LTC2945_MAX_VIN_THRES_H:
        case LTC2945_MIN_VIN_THRES_H:
                /* 25 mV resolution. */
                val = DIV_ROUND_CLOSEST_ULL(val, 25);
                break;
        case LTC2945_ADIN_H:
        case LTC2945_MAX_ADIN_H:
        case LTC2945_MIN_ADIN_THRES_H:
        case LTC2945_MAX_ADIN_THRES_H:
        case LTC2945_MIN_ADIN_H:
                /* 0.5mV resolution. */
                val *= 2;
                break;
        case LTC2945_SENSE_H:
        case LTC2945_MAX_SENSE_H:
        case LTC2945_MIN_SENSE_H:
        case LTC2945_MAX_SENSE_THRES_H:
        case LTC2945_MIN_SENSE_THRES_H:
                /* 25 uV resolution. Convert to  mA. */
                val *= shunt_resistor;
                /* Overflow check: Assuming 32-bit val and 32-bit shunt resistor, val is 64bits */
                val = DIV_ROUND_CLOSEST_ULL(val, 25 * 1000);
                /* Overflow check: val is now <= 50 bits */
                break;
        default:
                return -EINVAL;
        }
        return val;
}

static ssize_t ltc2945_value_show(struct device *dev,
                                  struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        long long value;

        value = ltc2945_reg_to_val(dev, attr->index);
        if (value < 0)
                return value;
        return sysfs_emit(buf, "%lld\n", value);
}

static ssize_t ltc2945_value_store(struct device *dev,
                                   struct device_attribute *da,
                                   const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct ltc2945_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u8 reg = attr->index;
        unsigned int val;
        u8 regbuf[3];
        int num_regs;
        long long regval;
        int ret;

        ret = kstrtouint(buf, 10, &val);
        if (ret)
                return ret;

        /* convert to register value, then clamp and write result */
        regval = ltc2945_val_to_reg(dev, reg, val);
        if (regval < 0)
                return regval;
        if (is_power_reg(reg)) {
                regval = clamp_val(regval, 0, 0xffffff);
                regbuf[0] = regval >> 16;
                regbuf[1] = (regval >> 8) & 0xff;
                regbuf[2] = regval;
                num_regs = 3;
        } else {
                regval = clamp_val(regval, 0, 0xfff) << 4;
                regbuf[0] = regval >> 8;
                regbuf[1] = regval & 0xff;
                num_regs = 2;
        }
        ret = regmap_bulk_write(regmap, reg, regbuf, num_regs);
        return ret < 0 ? ret : count;
}

static ssize_t ltc2945_history_store(struct device *dev,
                                     struct device_attribute *da,
                                     const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct ltc2945_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u8 reg = attr->index;
        int num_regs = is_power_reg(reg) ? 3 : 2;
        u8 buf_min[3] = { 0xff, 0xff, 0xff };
        u8 buf_max[3] = { 0, 0, 0 };
        unsigned long val;
        int ret;

        ret = kstrtoul(buf, 10, &val);
        if (ret)
                return ret;
        if (val != 1)
                return -EINVAL;

        ret = regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE,
                                 CONTROL_TEST_MODE);

        /* Reset minimum */
        ret = regmap_bulk_write(regmap, reg, buf_min, num_regs);
        if (ret)
                return ret;

        switch (reg) {
        case LTC2945_MIN_POWER_H:
                reg = LTC2945_MAX_POWER_H;
                break;
        case LTC2945_MIN_SENSE_H:
                reg = LTC2945_MAX_SENSE_H;
                break;
        case LTC2945_MIN_VIN_H:
                reg = LTC2945_MAX_VIN_H;
                break;
        case LTC2945_MIN_ADIN_H:
                reg = LTC2945_MAX_ADIN_H;
                break;
        default:
                WARN_ONCE(1, "Bad register: 0x%x\n", reg);
                return -EINVAL;
        }
        /* Reset maximum */
        ret = regmap_bulk_write(regmap, reg, buf_max, num_regs);

        /* Try resetting test mode even if there was an error */
        regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE, 0);

        return ret ? : count;
}

static ssize_t ltc2945_bool_show(struct device *dev,
                                 struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct ltc2945_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        unsigned int fault;
        int ret;

        ret = regmap_read(regmap, LTC2945_FAULT, &fault);
        if (ret < 0)
                return ret;

        fault &= attr->index;
        if (fault)              /* Clear reported faults in chip register */
                regmap_update_bits(regmap, LTC2945_FAULT, attr->index, 0);

        return sysfs_emit(buf, "%d\n", !!fault);
}

/* Input voltages */

static SENSOR_DEVICE_ATTR_RO(in1_input, ltc2945_value, LTC2945_VIN_H);
static SENSOR_DEVICE_ATTR_RW(in1_min, ltc2945_value, LTC2945_MIN_VIN_THRES_H);
static SENSOR_DEVICE_ATTR_RW(in1_max, ltc2945_value, LTC2945_MAX_VIN_THRES_H);
static SENSOR_DEVICE_ATTR_RO(in1_lowest, ltc2945_value, LTC2945_MIN_VIN_H);
static SENSOR_DEVICE_ATTR_RO(in1_highest, ltc2945_value, LTC2945_MAX_VIN_H);
static SENSOR_DEVICE_ATTR_WO(in1_reset_history, ltc2945_history,
                             LTC2945_MIN_VIN_H);

static SENSOR_DEVICE_ATTR_RO(in2_input, ltc2945_value, LTC2945_ADIN_H);
static SENSOR_DEVICE_ATTR_RW(in2_min, ltc2945_value, LTC2945_MIN_ADIN_THRES_H);
static SENSOR_DEVICE_ATTR_RW(in2_max, ltc2945_value, LTC2945_MAX_ADIN_THRES_H);
static SENSOR_DEVICE_ATTR_RO(in2_lowest, ltc2945_value, LTC2945_MIN_ADIN_H);
static SENSOR_DEVICE_ATTR_RO(in2_highest, ltc2945_value, LTC2945_MAX_ADIN_H);
static SENSOR_DEVICE_ATTR_WO(in2_reset_history, ltc2945_history,
                             LTC2945_MIN_ADIN_H);

/* Voltage alarms */

static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc2945_bool, FAULT_VIN_UV);
static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc2945_bool, FAULT_VIN_OV);
static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc2945_bool, FAULT_ADIN_UV);
static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc2945_bool, FAULT_ADIN_OV);

/* Currents (via sense resistor) */

static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc2945_value, LTC2945_SENSE_H);
static SENSOR_DEVICE_ATTR_RW(curr1_min, ltc2945_value,
                             LTC2945_MIN_SENSE_THRES_H);
static SENSOR_DEVICE_ATTR_RW(curr1_max, ltc2945_value,
                             LTC2945_MAX_SENSE_THRES_H);
static SENSOR_DEVICE_ATTR_RO(curr1_lowest, ltc2945_value, LTC2945_MIN_SENSE_H);
static SENSOR_DEVICE_ATTR_RO(curr1_highest, ltc2945_value,
                             LTC2945_MAX_SENSE_H);
static SENSOR_DEVICE_ATTR_WO(curr1_reset_history, ltc2945_history,
                             LTC2945_MIN_SENSE_H);

/* Current alarms */

static SENSOR_DEVICE_ATTR_RO(curr1_min_alarm, ltc2945_bool, FAULT_SENSE_UV);
static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc2945_bool, FAULT_SENSE_OV);

/* Power */

static SENSOR_DEVICE_ATTR_RO(power1_input, ltc2945_value, LTC2945_POWER_H);
static SENSOR_DEVICE_ATTR_RW(power1_min, ltc2945_value,
                             LTC2945_MIN_POWER_THRES_H);
static SENSOR_DEVICE_ATTR_RW(power1_max, ltc2945_value,
                             LTC2945_MAX_POWER_THRES_H);
static SENSOR_DEVICE_ATTR_RO(power1_input_lowest, ltc2945_value,
                             LTC2945_MIN_POWER_H);
static SENSOR_DEVICE_ATTR_RO(power1_input_highest, ltc2945_value,
                             LTC2945_MAX_POWER_H);
static SENSOR_DEVICE_ATTR_WO(power1_reset_history, ltc2945_history,
                             LTC2945_MIN_POWER_H);

/* Power alarms */

static SENSOR_DEVICE_ATTR_RO(power1_min_alarm, ltc2945_bool, FAULT_POWER_UV);
static SENSOR_DEVICE_ATTR_RO(power1_max_alarm, ltc2945_bool, FAULT_POWER_OV);

static struct attribute *ltc2945_attrs[] = {
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in1_min.dev_attr.attr,
        &sensor_dev_attr_in1_max.dev_attr.attr,
        &sensor_dev_attr_in1_lowest.dev_attr.attr,
        &sensor_dev_attr_in1_highest.dev_attr.attr,
        &sensor_dev_attr_in1_reset_history.dev_attr.attr,
        &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
        &sensor_dev_attr_in1_max_alarm.dev_attr.attr,

        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in2_min.dev_attr.attr,
        &sensor_dev_attr_in2_max.dev_attr.attr,
        &sensor_dev_attr_in2_lowest.dev_attr.attr,
        &sensor_dev_attr_in2_highest.dev_attr.attr,
        &sensor_dev_attr_in2_reset_history.dev_attr.attr,
        &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
        &sensor_dev_attr_in2_max_alarm.dev_attr.attr,

        &sensor_dev_attr_curr1_input.dev_attr.attr,
        &sensor_dev_attr_curr1_min.dev_attr.attr,
        &sensor_dev_attr_curr1_max.dev_attr.attr,
        &sensor_dev_attr_curr1_lowest.dev_attr.attr,
        &sensor_dev_attr_curr1_highest.dev_attr.attr,
        &sensor_dev_attr_curr1_reset_history.dev_attr.attr,
        &sensor_dev_attr_curr1_min_alarm.dev_attr.attr,
        &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

        &sensor_dev_attr_power1_input.dev_attr.attr,
        &sensor_dev_attr_power1_min.dev_attr.attr,
        &sensor_dev_attr_power1_max.dev_attr.attr,
        &sensor_dev_attr_power1_input_lowest.dev_attr.attr,
        &sensor_dev_attr_power1_input_highest.dev_attr.attr,
        &sensor_dev_attr_power1_reset_history.dev_attr.attr,
        &sensor_dev_attr_power1_min_alarm.dev_attr.attr,
        &sensor_dev_attr_power1_max_alarm.dev_attr.attr,

        NULL,
};
ATTRIBUTE_GROUPS(ltc2945);

static const struct regmap_config ltc2945_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = LTC2945_MIN_ADIN_THRES_L,
};

static int ltc2945_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct regmap *regmap;
        struct ltc2945_data *data;

        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
        dev_set_drvdata(dev, data);

        regmap = devm_regmap_init_i2c(client, &ltc2945_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(dev, "failed to allocate register map\n");
                return PTR_ERR(regmap);
        }

        data->regmap = regmap;
        if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
                                     &data->shunt_resistor))
                data->shunt_resistor = 1000;

        if (data->shunt_resistor == 0)
                return -EINVAL;

        /* Clear faults */
        regmap_write(regmap, LTC2945_FAULT, 0x00);

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data,
                                                           ltc2945_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ltc2945_id[] = {
        {"ltc2945"},
        { }
};

MODULE_DEVICE_TABLE(i2c, ltc2945_id);

static struct i2c_driver ltc2945_driver = {
        .driver = {
                .name = "ltc2945",
                .of_match_table = of_match_ptr(ltc2945_of_match),
        },
        .probe = ltc2945_probe,
        .id_table = ltc2945_id,
};

module_i2c_driver(ltc2945_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("LTC2945 driver");
MODULE_LICENSE("GPL");